Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds meaningful non-schema behavior: the price is $0.002 USDC per successful call via x402, failed calls are not charged, and payment can occur on Base, Solana, or Arc.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single front-loaded sentence that identifies the series, default mnemonic, observation count, and pricing model. Every clause contributes relevant information for an agent deciding whether and how to call the tool.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so the description need not explain return values, and annotations plus schema cover the safety and parameter basics. It is nearly complete for invocation, though it lacks explicit routing guidance against the many sibling finance tools.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so both parameters are already documented. The description adds only a little beyond the schema by clarifying that the default FNYR-SOFR-A mnemonic represents the SOFR rate in percent, which is useful but not substantial.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states a specific resource: the OFR Short-term Funding Monitor daily series, with one mnemonic and the latest N observations. It is distinguishable from generic finance tools by naming the OFR source and default SOFR series, though it does not explicitly contrast itself with any sibling tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explains what the tool returns and its default mnemonic, but gives no explicit guidance on when to choose this tool versus other finance or crypto data tools. There are no when-not conditions or named alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.